Fix remaining errors and enable strict mode (#1628)

## Description:

#1075 

Fixing all remaining type errors caused by strict mode and enable it.

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced
- [x] I have read and accepted the CLA agreement (only required once).

## Please put your Discord username so you can be contacted if a bug or
regression is found:

azlod

---------

Co-authored-by: Scott Anderson <662325+scottanderson@users.noreply.github.com>

src/core/execution/PlayerExecution.ts

@@ -1,7 +1,7 @@
 import { Config } from "../configuration/Config";
 import { Execution, Game, Player, UnitType } from "../game/Game";
 import { GameImpl } from "../game/GameImpl";
-import { TileRef } from "../game/GameMap";
+import { GameMap, TileRef } from "../game/GameMap";
 import { calculateBoundingBox, getMode, inscribed, simpleHash } from "../Util";
 
 export class PlayerExecution implements Execution {
@@ -190,7 +190,11 @@ export class PlayerExecution implements Execution {
     }
 
     const firstTile = cluster.values().next().value;
-    const filter = (_, t: TileRef): boolean =>
+    if (!firstTile) {
+      return;
+    }
+
+    const filter = (_: GameMap, t: TileRef): boolean =>
       this.mg?.ownerID(t) === this.player?.smallID();
     const tiles = this.mg.bfs(firstTile, filter);